At each McDonald's store, a new service "Tomato Topping" that allows you to top burgers with "sliced tomatoes" will start at 10:30 on August 4th. The price is 40 yen (tax included).

Add tomatoes to your favorite burger! (The image is an image)
Add tomatoes to your favorite burger! (The image is an image)

This means that all burgers offered during the "regular hours (from 10:30 am to closing)" can be topped with one "sliced tomato" for an additional charge of 40 yen. It seems that you can topping up to 3 fresh tomatoes sliced at the store (+40 yen for each additional one).